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Old 6th December 2010, 10:17 AM   #261
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hi apex, I recently found a lot of original motorola 2N3773 trannies.Now i want to make a powerfull amp by using these.I am interested in B550. I have some questions.
1.What is the maximum psu voltage with the maxmum no. of 2N37773 for max.output with this circuit.
2.I think this circuit is only suitable for bass amp ?
3. MJE drivers are hard to find here,2sa1943/2sc5200 is easily available though these are o/p devices , i think it can be used for drivers also.
4.With above drivers how many pairs of 2N3773 is needed for bridge application
One thing more that i am not merely putting questions but i am going to make this amp within some weeks so a reply from you will be highly helpful for me.
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Old 6th December 2010, 12:55 PM   #262
AndrewT is offline AndrewT  Scotland
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3773 have max Vce0=140V.
I recommend no more than +-65Vdc for a power supply.

For bridged you must design each half with the ability to properly drive a reactive load impedance of half your speaker impedance.
If you have 8ohm speaker, then you design the amp to drive 4ohm and/or 1r5 from the supply rails.

If you have a 4ohm speaker, then your challenges are going to stretch you.

Expect the output stage total wattage to be between 5 to 6times the expected maximum output power.
+-65Vdc will give ~200W into 8r0 and ~400W into 4r0.
to drive 400W into 4r0 then expect ~2000W to 2400W of BJT output stage power dissipation capability.
You need two of these to get your 800W into 8ohm amplifier so total output pairs is ~ 4400/150=~30pairs (15pair in each half). Yes, 60 2n3773 for a bridged Quasi driving 800W into 8r0.
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Last edited by AndrewT; 6th December 2010 at 01:01 PM.
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Old 7th December 2010, 03:22 AM   #263
boytaho is offline boytaho  Philippines
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Quote:
Originally Posted by AndrewT View Post
3773 have max Vce0=140V.
I recommend no more than +-65Vdc for a power supply.

For bridged you must design each half with the ability to properly drive a reactive load impedance of half your speaker impedance.
If you have 8ohm speaker, then you design the amp to drive 4ohm and/or 1r5 from the supply rails.

If you have a 4ohm speaker, then your challenges are going to stretch you.

Expect the output stage total wattage to be between 5 to 6times the expected maximum output power.
+-65Vdc will give ~200W into 8r0 and ~400W into 4r0.
to drive 400W into 4r0 then expect ~2000W to 2400W of BJT output stage power dissipation capability.
You need two of these to get your 800W into 8ohm amplifier so total output pairs is ~ 4400/150=~30pairs (15pair in each half). Yes, 60 2n3773 for a bridged Quasi driving 800W into 8r0.



i have built this amp

http://i907.photobucket.com/albums/a...t/IMG_0875.jpg
http://i907.photobucket.com/albums/a...t/IMG_0876.jpg
http://i907.photobucket.com/albums/a...t/IMG_0877.jpg

with 2n5551, mje150332/33, and 6 pairs of 2sc5200

my question, can i feed it with +-90v???

any suggestions pls..
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Old 7th December 2010, 03:55 AM   #264
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Join Date: Dec 2008
Location: bangalore
Quote:
Originally Posted by AndrewT View Post
3773 have max Vce0=140V.
I recommend no more than +-65Vdc for a power supply.

For bridged you must design each half with the ability to properly drive a reactive load impedance of half your speaker impedance.
If you have 8ohm speaker, then you design the amp to drive 4ohm and/or 1r5 from the supply rails.

If you have a 4ohm speaker, then your challenges are going to stretch you.

Expect the output stage total wattage to be between 5 to 6times the expected maximum output power.
+-65Vdc will give ~200W into 8r0 and ~400W into 4r0.
to drive 400W into 4r0 then expect ~2000W to 2400W of BJT output stage power dissipation capability.
You need two of these to get your 800W into 8ohm amplifier so total output pairs is ~ 4400/150=~30pairs (15pair in each half). Yes, 60 2n3773 for a bridged Quasi driving 800W into 8r0.
Thanks for reply, Can you suggest some other circuit using 2N377 with better configuration.I think that at least this circuit must have some type of current adjusment desiging for o/p transistor.Is it safe to add so much of trannies without current adjustment circuitry.
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Old 7th December 2010, 04:00 AM   #265
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Location: bangalore
Quote:
Originally Posted by boytaho View Post
i have built this amp

http://i907.photobucket.com/albums/a...t/IMG_0875.jpg
http://i907.photobucket.com/albums/a...t/IMG_0876.jpg
http://i907.photobucket.com/albums/a...t/IMG_0877.jpg

with 2n5551, mje150332/33, and 6 pairs of 2sc5200

my question, can i feed it with +-90v???

any suggestions pls..
What about the performance like noise,stability,heating,power etc.
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Old 7th December 2010, 09:55 AM   #266
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Location: bangalore
can i use any coplementry symmetry design for quasi design if i change the arrangemet of o/p devices as in quasi designs?sorry for a littlel bit confused question
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Old 7th December 2010, 10:11 AM   #267
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
go and read the various threads created for Quasi's collection of quasi complementary designs (both FET & BJT versions).
He also has a website where details of schematics and PCBs are located.
The threads will show you how to get a quasi to work.
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Old 7th December 2010, 12:32 PM   #268
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Quote:
Originally Posted by sudhir kumar View Post
hi apex, I recently found a lot of original motorola 2N3773 trannies.Now i want to make a powerfull amp by using these.I am interested in B550. I have some questions.
1.What is the maximum psu voltage with the maxmum no. of 2N37773 for max.output with this circuit.
2.I think this circuit is only suitable for bass amp ?
3. MJE drivers are hard to find here,2sa1943/2sc5200 is easily available though these are o/p devices , i think it can be used for drivers also.
4.With above drivers how many pairs of 2N3773 is needed for bridge application
One thing more that i am not merely putting questions but i am going to make this amp within some weeks so a reply from you will be highly helpful for me.
I suggest you to start with basic version, and upgrade later,
Regards
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Old 8th December 2010, 06:36 AM   #269
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Quote:
Originally Posted by apexaudio View Post
I suggest you to start with basic version, and upgrade later,
Regards
Thanks for reply sir,
I have already made simple amps like p3a with a1943/c5200 and a simple quasi using 2n3773 with +/-35 psu and i want to upgrade my quasi thats why i am asking these questions.
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Old 8th December 2010, 08:53 AM   #270
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Quote:
Originally Posted by sudhir kumar View Post
Thanks for reply sir,
I have already made simple amps like p3a with a1943/c5200 and a simple quasi using 2n3773 with +/-35 psu and i want to upgrade my quasi thats why i am asking these questions.
I suggest +/-65V DC rail voltage with 4 pairs 2N3773 in output stage as best version of this amp.
Regards
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